Service providers or carriers typically offer numerous voice and data services to end users of mobile phones or other mobile terminals. Some examples of voice services are voice calls, call forwarding, call waiting, etc. Some examples of data services are Internet access, streaming audio, streaming video, online gaming, Internet Protocol television (IP-TV), etc. A “carrier” is a term commonly used in the United States and Canada to refer to a company that provides these types of voice or data services. Examples of carriers include Verizon Wireless®, T-Mobile®, AT&T®, etc.
The first types of wireless or mobile networks that were introduced by carriers were First Generation (1G) and Second Generation (2G) networks. 1G networks provided voice services via analog signals, and then evolved into 2G networks that provided voice services via digital signals. Mobile communications then evolved into Third Generation (3G) (including 2.5G) networks that provided both voice services and data services. For example, 3G networks are able to provide wireless voice telephony, as well as data services such as Internet access, video calls, mobile TV, etc. Some of the 3G networks implemented by carriers were Universal Mobile Telecommunications System (UMTS) networks, Enhanced Voice Data Optimized (EV-DO) networks, General Packet Radio Service (GPRS) networks, etc. Carriers are now migrating their networks toward Fourth Generation (4G) technologies over Packet-Switched (PS) networks. 4G networks are essentially enhancements to 3G networks in terms of data speeds. For example, a 3G network can provide data speeds of about 3.5 Mbit/sec. According to the International Telecommunication Union (ITU), a 4G network can provide data speeds of 100 Mbit/sec. One project within the 3rd Generation Partnership Project (3GPP, 3GPP2) is the Long Term Evolution (LTE), which is a 4G technology. The network architecture defined by this project is referred to as the Evolved Packet System (EPS). The EPS architecture comprehends E-UTRAN (Evolved-UMTS Terrestrial Radio Access Network) on the radio access side and EPC (Evolved Packet Core) on the core side. Fifth Generation (5G) denotes the next major phase of mobile telecommunications standards beyond the current 4G standards.
E-UTRAN is the air interface of the LTE network, and comprises a plurality of base stations that are referred to as Enhanced NodeBs (eNodeBs). NodeB is a term used in UMTS to refer to a base station or cell site that interfaces a mobile device with a core network (similar to a base transceiver station (BTS) in a GSM network). The coverage area surrounding the base station is referred to as a “cell”. An eNodeB is comprised of multiple cells or sectors, and is an enhanced base station that performs tasks similar to a nodeB in communicating with mobile devices.
Wireless technologies utilized by base stations use the airwaves to transmit and receive information. Because different technologies can use the airwaves simultaneously, the wireless or radio-frequency (RF) spectrum is segmented into frequency bands. Regulatory agencies, such as the Federal Communications Commission (FCC) in the United States, define a licensed spectrum where carriers are allowed to operate. A regulatory agency uses spectrum allocation to issue exclusive rights to carriers to operate within certain frequency bands on the licensed spectrum. Spectrum allocation ensures that carriers do not interfere with each other's transmissions.
Other frequency ranges in the RF spectrum is unlicensed, and is referred to as the “unlicensed spectrum”. One example of the unlicensed spectrum is the 5 GHz band used by dual-band Wi-Fi equipment. Modern mobile phones have RF capabilities for communicating over the unlicensed spectrum in addition to the licensed spectrum of a carrier. Proposals have been made to provide carrier-grade wireless service on the unlicensed spectrum, such as LTE-U (LTE-Unlicensed), License Assisted Access (LAA), and LTE-WLAN Aggregation (LWA). The unlicensed spectrum can be used as a complement to the licensed spectrum to help carriers address the increased traffic on their networks. It is therefore desirable to effectively utilize the unlicensed spectrum for carrier-grade wireless services.